1. Field of the Invention
The present invention relates to a projector having a light source, an electric optical device for modulating a light beam irradiated from the light source in accordance with image information to form an optical image, a projecting optical system for enlarging and projecting the optical image formed by the electric optical device, and a casing for accommodating these components.
2. Description of Related Art
Conventionally, a projector having a light source, an electric optical device for modulating a light beam irradiated from the light source in accordance with image information to form an optical image, a projecting optical system for enlarging and projecting the optical image formed by the electric optical device, and a casing for accommodating these components has been used.
Such projectors have been widely used for multimedia presentation in a meeting, scientific society, exhibition etc. Accordingly, in order to obtain vivid projected image by the projector, it is required for the light source to increase luminance thereof.
In order to enhance the luminance of the light source of the projector, cooling efficiency of optical components including the electric optical device has to be improved for preventing overheat in the inside of the device.
Accordingly, a suction fan and an exhaust fan provided in the projector for cooling is enlarged to promote the circulation of the cooling air, thus enhancing the cooling efficiency.
However, following problems accompanies in the above arrangement where the fan is enlarged in accordance with increasing the luminance of the light source for enhancing the cooling efficiency. When the size of the fan is increased to promote circulation of the cooling air inside the device, flow rate and speed of the cooling air are naturally increased, which causes jet noise in colliding with the components constituting the projector, so that noise is likely to be generated in using the projector.
Especially, when the exhaust fan is provided along the exterior case of the projector, size increase of the fan results in increase in the sound of the exhaust fan itself as well as the jet noise, thus further increasing the noise.
Further, in the conventional projector, since the cooling air is exhausted from a backside of the device opposite to the portion provided with the projecting optical system, hot wind is blown to the audience observing the projected image, which is annoying to the audience. When the size of the exhaust fan is enlarged, the above tendency is expected to be strengthened.
An object of the present invention is to respond to improving cooling efficiency inside the device in accordance with increase in luminance of the light source, to secure sufficient silence and to prevent annoyance to the audience. Specifically, the present invention is arranged as follows.
A projector according to the present invention includes: a light source; an electric optical device for modulating a light irradiated from the light source in accordance with an image information to form an optical image; a projecting optical system for enlarging and projecting the optical image formed by the electric optical device; a casing for accommodating the light source, the electric optical device and the projecting optical system; a centrifugal fan disposed around the light source for inhaling an air by a rotation thereof and for discharging the air in tangential direction of the rotation; an exhaust duct accommodated in the casing, the exhaust duct having a first end connected to an air discharge hole of the centrifugal fan and a second end connected to an exhaust hole formed at the front of the casing for the projecting optical system to be exposed; and at least one bent portion formed on the exhaust duct to bend an exhaust stream discharged from the centrifugal fan.
As the centrifugal fan, a fan for inhaling air from a rotary surface of a fan and discharging in tangential direction of the rotation of the vane, which may be a sirocco fan etc. The centrifugal fan inhales air with a large opening area and discharges the air with a small opening area, so that the discharge pressure of the discharged air can be magnified.
According to the above arrangement, since the exhaust hole formed on the casing and the centrifugal fan for exhausting the air are connected through the exhaust duct, the centrifugal fan for exhausting the air can be located remote from the exhaust hole, so that the noise generated by the projector can be reduced even when the size of the cooling fan is increased.
Since the exhaust air is discharged from the exhaust hole through the inside of the exhaust duct, the exhaust stream can be prevented from colliding with components of the projector, thereby restraining generation of jet noise and improving silence of the projector.
Since the bent portion is formed on the exhaust duct, the noise of the exhaust fan can be prevented from being leaked out of the exhaust hole, thereby further improving silence of the projector.
Since the centrifugal fan such as a sirocco fan is used as the exhausting fan, the air can be discharged with a high discharge pressure, so that the air can be sufficiently discharged even when the length of the exhaust duct from the air discharge hole of the centrifugal fan to the exhaust hole of the casing is lengthened.
Since the exhaust hole is provided on the front side of the projector, the hot wind does not blow out from the backside of the projector, so that audience observing the projected image of the projector does not feel annoyed.
In the present invention, the casing may preferably be approximately rectangular solid, and the exhaust duct may preferably extend along at least two sides of the inside of the casing.
According to the above arrangement, since the exhaust duct can be located on the outermost portion of the case and the respective optical components can be efficiently disposed inside the case, thereby improving accommodation efficiency and preventing increase in size of the device.
In the present invention, the cross section of the exhaust duct may preferably have a larger diameter along the inside of the casing than the diameter in a direction orthogonal with the inside of the casing.
According to the above arrangement, the exhaust efficiency is not impaired, and since the diameter in one direction is small, the optical components can be disposed at the spare space, thereby improving accommodation efficiency and preventing increase in device size.
In the present invention, the bending angle of the bent portion may preferably be 45 degrees or less.
According to the above arrangement, turbulence can be restrained and the exhaust stream can smoothly flow even at the bent portion.
In the present invention, an optical component case for accommodating optical components including the light source may preferably be provided, the exhaust duct being disposed along the optical component case, and an intake duct provided between the optical component case and the exhaust duct to introduce components inside the optical component case to an air intake of the centrifugal fan.
According to the above arrangement, the after-cooling air of the portion where the heat is the most likely to be accumulated can be guided to the air intake of the centrifugal fan.
In the present invention, an opening for introducing the cooling air formed on a side of the optical component case opposite to a side along with the intake duct may preferably be provided, a disposition of the opening corresponds to a disposition of the optical components accommodated in the optical component case.
According to the above arrangement, since the cooling air from above the optical component case can be introduced to the intake duct, the air flow inside the optical component casing can be made smooth, thereby efficiently cooling the components.
In the present invention, an exhaust opening for discharging the air having cooled the optical components may preferably be formed on the optical component case, a disposition of the exhaust opening corresponds to a disposition of the light source accommodated therein, the centrifugal fan may preferably be disposed on the exhaust opening with the air intake of the centrifugal fan being faced, and a partition member for dividing an after-cooling air transferred from the light source and an after-cooling air transferred from the other optical components may preferably be provided to the exhaust opening.
According to the above arrangement, the after-cooling air of different portions in the optical component case can be securely guided to the air intake of the centrifugal fan by the partition members.
In the present invention, a light source partition for dividing the after-cooling air transferred from a light-irradiating side of the light source and the after-cooling air transferred from the backside of the light source may preferably be provided to the exhaust opening.
According to the above arrangement, the after-cooling air from the light-irradiating side and backside of the light source can be securely introduced to the air intake of the centrifugal fan by the partition members.
In the present invention, the intake duct may preferably be constructed by combining a recess formed on the outside of the optical component case and a lid member shutting the recess, the lid member and the partition member being integrated.
According to the above arrangement, the lid member and the partition members do not have to be manufactured as separate components, thereby omitting work and components required therefor.